PHOSPHATE EQUILIBRIUM BETWEEN STREAM SEDIMENTS AND WATER: POTENTIAL EFFECT OF CHEMICAL AMENDMENTS

摘要

Sediments often play an important role in the temporary storage and release of phosphorus (P) in streams, especially streams receiving municipal wastewater treatment plant (WWTP) effluent. The objective of this study was to evaluate sediment-aqueous phase P equilibrium in four Ozark streams, and to determine the effect of alum (Al{sub}2(SO{sub}4){sub}3) and calcium carbonate (CaCO{sub}3) on stream sediment-P interactions and content of exchangeable P. Stream physicochemical properties were significantly affected by the effluent discharge from the WWTPs; of particular interest to this study was that the increase in P concentrations varied greatly among streams. Phosphorus inputs from WWTP significantly increased sediment equilibrium P concentrations (sediment-EPC{sub}0) and readily exchangeable sediment-bound P, while decreasing the P buffering capacity of stream sediments. Sediment-EPC{sub}0 values were as great as 7 mg L{sup}(-1) downstream from one WWTP, suggesting that sediments are a transient storage pool of P and may release P back into the stream system when P inputs from the WWTP are reduced. The addition of alum and CaCO{sub}3 significantly reduced the sediment-EPC{sub}0 and readily exchangeable P, while increasing the ability of sediments to buffer increasing P loads.